Airplane



June 28, 1932. w, DT 1,864,996

AIRPLANE- Original FiledJune 29. 1927 2 Sheets-Sheet l I Ilia-1.!

INVENTOR.

-A TTORNEYS.

n 1932- w; F. GERHARDT 5 6 AIRPLANE Original Filed June 29, 1927 2 sheets-she t 2 INVENTOR. M 3

ATTORNEYS Patented June 28, 1932 WILLIAM F. GERHARDT, OF ANN ARBOR, MICHIGAN AIRPLANE Application filed June 29, 1927, Serial No. 202,351.

This invention relates to airplanes and particularly to the structural, aerodynamical and control features thereof.

One object of the invention is the provision 6 of a tailless airplane which will be stable-in flight and which may be easily controlled.

Another object of the invention is the pro vision of an airplane in which the lifting and control aerofoils will be efliciently arranged. 19 A further object of the invention is the provision of control means for an aircraft which will be capable of automatically maintaining the attitude of the craft while in flight. 15 Still further objects and advantages of the invention will be apparent from the following description and from the accompanying drawings in which;

Fig. 1 is a front elevation of an airplane embodying one form of the present invention;

Fig. 2 is a top plan view of the airplane;

Fig. 3 is a side elevation of the airplane; I Fig. 4 is an end view of the control aerofoils by which laterallyand longitudinal sta bility of the aircraft is effected;

Fig. 5 is a front elevation of the control aerofoils;

Fig. 6 is a top plan view of the control aerofoils shown in Figs. 4 and 5;

Fig. 7 is a diagrammatic view showing the manner in which the control aerofoils of the airplane areconnected to the manual con- I trol lever; v

' Fig. 8 is a side elevation of a modified form of construction of the control aerofoils; and

Fig. 9 is a front elevation corresponding to Fig. 8.

Referring more particularly to the drawings by reference numerals in which corre sponding numerals designate like parts in the various views, the airplane in which the pres ent invention is embodied is shown provided r with a number of long narrow sustaining planes or surfaces 10, 11, 12 and 13 positioned one above the level of the other. Each sus taining surface has a much higher aspect ratio than the sustaining surfaces at present customarily employed in airplanes, but the uppermost and lowermost planes 13 and Renewed November 16, 1931. I

are of considerably greater chord length than that of the intermediate planes 11 and 12. The sustaining planes are spaced apart ver tically a distance approximately equal to several times the mean chord length of the planes, and they are rigidly held in this relationship by means of vertically extending struts 14, 15 and 16 which preferably extend from the uppermost to the lowermost plane and through the two intermediate planes so that they will all be definitely spaced apart. Tie wires 17, 18 and 19 extending along'the front and rear edges of the planes and be tween the various planes interbrace the planes in such a manner as to form a rigid cellule which is of considerable height and width but of very small depth. The total height of the cellule is nearly equal to its total width in a direction transverse to the line of flight and it has been found that by arranging the 7 planes generally as just specified so that a series of widely separated, very narrow planes of an exceedingly high aspect ratio are formed into a cellule of great height, an exceedingly efficient aerodynamica-l arrange ment is obtained in which the lift of the planes will be quite large in proportionto the drag and the weight of the cellule. The upper and lower planes being of considerably greater chord length than the intermediate 0 planes also provides for an eflicient utilization of the air reaction so that a 111inirnum of interference is obtained in the air reactions of adjacent planes.

The various lifting planes 10, 11, 12 and 13 3 form a rigid cellule which is indicated generally 20. This cellule is fastened at its lower central portion to a car or body frame 21. Suitably tensioned guy-wires 22 and 23 connect the upper portions of the cellule to the front and rear portions of the car 21 so that the two are held rigidly together. At the forward portion of the car frame is a propeller 24 adapted to be rotated either manu ally or by any suitable source of power. The pilots position is slightly in front of the wing cellule as indicated in Fig. 3 and at this point the car frame is enlarged as indicated at 25 so that it may suitably receive the pilot of the airplane. The forward and rear portions of the car are preferably of minimum width as indicated in Fig. 2 and the car framework may be made quite light as the strain which is imposed on it is erceedlngly small, the car being entirely devoid of the horizontal and vertical control surfaces usually provided in prior constructions at the rear portion of the same. The car is quite short in its longitudinal extent thus aiding in the more direct distribution of stresses and forces to the wing cellule which is arranged so that the planes have a backward stagger while in flight. The wing cellule is preferably so arranged in relation to the car and propeller that the flying attitude substantially corresponds with the position or attitude when the craft is at rest on the ground. At its lower central portion the car is provided with a landing gear 26 of any suit-able construction, on which the airplane is supported while on the ground, suitable wing skids 27 and 28 being provided at the lateral portions of the lower plane 10 for maintaining the end portions of the plane suitably spaced above the level of the ground when the airplane is at rest or when it is taXying over the surface of the ground. At the rear of the car is a landing member or wheel 29 which supports the rear portion of the car when the airplane is at rest on the ground.

As previously mentioned the airplane body or frame 21 is of exceptionally short length and is entirely devoid of the customary control tail at its rear end. Directional control of the airplane is effected by means of two vertical rudders 30 and 31 suitably positioned between two adjacent planes such as the planes 10 and 11 and located at the outer portions of the cellule where they will be a considerable distance away from the center of gravity of the airplane indicated at 32.

Since the rudders are spaced away from the center of the airplane it is evident that any turning effect which is imparted to one or to both of the rudders will be effective in turning the airplane for directional control. The two rudders 30 and 31 are preferably slightly inclined to the line of flight in their normal positions, and are preferably pivoted in front of their centers of pressure as indicated at 32 and 33 (Fig. 7 The front portions of these two rudders are interconnected by means of the control cable .34, and the rear portions of the rudders are preferably urged to some normal position by means of the springs 35 which act against the pull of the control cable 34 to swing the rudders when the cable is slackened. The control cable 34, adjacent the pilots position 25, is connected to an arm 36 which extends rearwardly from the control lever 37. The control lever as herein shown is mounted for universal movement about a point 38 so that it may be rotated about its own longitudinal up and down axis to pull upon one end of the control cable 34 and re- H lease the other and thus increase the air resistance of one rudder while the resistance of the other rudder is decreased, thus causing a braking effect and increased resistance of the plane which is pulled by the control cable to turn the airplane about a vertical axis for the control of the direction of flight.

The airplane is provided with control s11r faces for maintaining its proper attitude in an inherently automatic manner. The control surfaces are also adapted to be manually operated so that the craft may be controlled as desired by the pilot. As the length of the car is exceedingly small the control surfaces for controlling the longitudinal and lateral movements of the craft are positioned on the sustaining cellule and at a considerable distancefrom the center of gravity of the airplane, as indicated at 82. Thus each side portion of the upper plane 13 is provided with a control aerofoil 40 which is mounted for pivotal movements on an axis 41 located a substantial distance to the rear of its center of pressure indicated at 42. The pivot axis extends substantially transverse of the line of flight, and the supporting members 43 and 44 form a rigid frame at the end of the upper plane in which the aerofoil is pivoted. The aerofoil 40 is preferably inclined upwardly and outwardly so that it is given a positive dihedral and it is positioned somewhat above the top of the upper plane and preferably laterally beyond the end of the plane where it is subjected to an upflow of air created by the wing tip vortex. The wing tip is preferably provided with a fixed depending fin 45 which is fastened below the outer portion of the wing so that it will be parallel to the line of flight. The air which rushes from below the outer part of the wing around the wing tip and around the fin 45 will have a movement upward rearward as indicated by the arrows 46 and 47 in Figs. 1 and 4 respectively. The aerofoil 40 being positioned above the level of the wing tip and located outwardly from it will be subject to a rush of air traveling upwardly and rearwardly. Consequently when the aerofoil 40 is positioned as shown in Fig. 4 so that it inclines downwardly at its forward portion, it will be exerting a lifting force while in flight since the angle of incidence of the aerofoil is positive in relation to the flow of air to which the aerofoil is subjected, which will be approximately in the direction of the arrow 47. The air reaction on the aerofoil 40 will therefore be approximately in the direction indicated by the arrow 48 which extends downwardly and rearwardly, and since the aerofoil 40 is at a positive dihedral angle the air reaction will furthermore be directed outwardly as well as downwardly as indicated by the arrow 49 in Fig. 1. The arrow 48 corresponds to the direction of the air reaction line 50 (see Fig. 3) when the airplane is in normal flight. The line of air reaction 50 of control aerofoil 40 will thus be seen to extend a considerable distance to the rear of the center of gravity of the airplane and thus produce a considerable moment effective in controlling the airplane.

The control aerofoil 40 is connected to a second aerofoil 52 which is suitably spaced therefrom and as shown in Fig. 4, is located below the aerofoil 40. This second aerofoil may be slightly smaller in chord length and is pivoted as indicated at 53 a considerable distance in front of its own normal center of pressure 54. The aerofoil 52 is mounted in the frame members 43 and 44 so that it is positioned preferably horizontally adjacent the rear portion of the end of the upper sustaining plane 13. Like the aerofoil 40 the vane 52 is at a positive angle of incidence to the airflow to which the vane is subjected and thus the line of lift of the vane extends downwardly and rearwardly approximately in the direction of the line which indicates the normal effective angle of lift of the combined aerofoils 40 and 52. The two aerofoils 40 and 52 are interconnected by means of an adjustable tie designated generally 55 which interconnects their forward portions together so that as one moves the other is likewise forced to move about its pivot through a correspondingly proportionate angle. The interconnection 55 comprises a bell-crank lever 56 pivoted at the point 57 on a rigid arm or horn 58 which extends forwardly from the front portion of the vane 52. Attached to the rear arm of the bell-crank lever is the rigid strut 59 the upper end of which is connected at a point 60 in front of the pivotal axis 41 of the upper aerofoil 40. One arm of the bell-crank 56 extends upwardly and is connected to a control cable 61 which is guided at 62 adjacent the leading edge of the sustaining plane 13 and extends to the pilots station in the car body where it is connected to the control stick 37. A suitable spring. 63 acts against the pull of the cable 61 and normally tends to decrease length of the interconnections 55 between the two aerofoils. The length of the connection 55 may thus be controlled manually by operating the control stick 37, the lower end of which is provided with a suitable sleeve 64 to which cable 61 is attached so that when the control stick is pulled rearwardly as shown by the arrow in Fig. 7, the cable 61 will be slackened and the spring 63 will be effective in shortening the distance between the leading edges of the two aerofoils.

The aerofoils 40 and 52 preferably are normally in stable balance so that the upper aerofoil is at the greater angle of incidence or in other words so that a decalageis provided between the surfaces. The connection of the strut 59 to the upper aerofoil is considerably ahead of the center of pressure and of the center of rotation of the acrofoil, and the strut is effective on aerofoil 52 at a distance comparatively close to its pivot axis, consequently the angular movements of the surface 52 will be in excess of those imparted to the upper surface. The two aerofoils 40 and 52 automatically balance their positions in the air rush so that both surfaces are normally at a positive angle of incidence. Any tendency of the lower aerofoil to decrease its angle of incidence is resisted by a correspondingly opposite tendency of the upper surface and they thus normally assume a position of equilibrium in which both planes are at some positive angle of incidence to the air flow past them. Each side of the airplane is provided with a similar system of control aerofoils as just described by means of which the lateral and longitudinal stability of the airplane is maintained or controlled.

The areofoils 40 and 52 operate automatically to maintain lateral stability in the following manner: Considering the system on one side of the airplane as at the right in Fig. 1, the aerofoils 40 and 52 are normally in stable balance at some positive angle of incidence and the resultant lift of the two aerofoils will normally be in the direction of the line 50 of Fig. 3. If a side slip towards the right starts to occur the areofoil 40 will be effected more than the aerofoil 52 since the aerofoil 40 is at a positive dihedral, and'the center of pressure of this aerofoilbeing in front of its pivot axis, the effective angle of incidence of the surface will be increased. The tendency of the lower aerofoil to decrease its angle of incidence will be overbalanced by the opposite tendency of aerofoil 40 and consequently the resultant lift of both surfaces will be increased, and both aerofoils will be moved to some new position of balance in which they will tend to raise the low side of the airplane to bring it back to its normal attitude. An exactly opposite sequence of event takes place on the opposite side of the airplane since the side slip will be less effective on the upper inclined aerofoil 40 than on the horizontal aerofoil 52 and consequently these two aerofoils will assume some new position. of balance, both at less angles of incidence than they were before and consequently both exerting less lift and tending to right the airplane. The two opposite control systems also automatically operate to govern and maintain longitudinal stability of the craft. Ordinarily by reason of the rearwardly stagger of the sustaining surfaces and by reason of the upflow of air out from under the wing tip the control surfaces 40 and 52 exert some upward force directed along the line 50 which is some considerable distance to the rear of the center of gravity 32. thus resulting in a considerable moment which is ordinarily balanced by the other forces such as the propeller thrust, drag, etc. Should the airplane start to dive the control aerofoils l0 and 52 automatically .adjust themselves about their centers or rotation to correct this tendency by adjusting the line on which their resultant lift is effective. When diving the sustaining effect of the control aerofoils l0 and 52 remains approximately the same as its normal value since these two planes automatically adjust themselves to their normal predetermined angle of incidence in relation to the air which passes them. he direction of this force however is much closer to the center of gravity when diving than it was before since the upper part of the wing cellule is considerably ahead of the center gravity in this position, and the effect of this readjustment of the control aerofoils is to decrease the diving movement so as to cause the airplane to automatically assume its normal proper position of flight. The line 65 shows the approximate limit of travel of the lift reaction of the control aerofoils, and shows the direction of this force when the airplane is in the diving attitude. hen the airplane is in the stalling attitude the line 66 (Fig. 3), shows the direction in which the lift of the control aerofoils is effective. lVhen stalling the amount of lift along the line 66 is substantially the same as the normal lift along the line but since the line 66 is inclined rearwardly at a greater angle, a correspondingly greater mom nt is efiective in causing the airplane to assume its normal position of flight.

The various movements of the planes 40 and 52 in automatically maintaining the longitudinal and lateral stability of the airplane will. not be effected by the connection of the adjustable tie 55 with the manual control means. For controlling the movements of the airplane as desired by the pilot the adjustable tie 55 may be regulated in its effective length by manipulation of the operating cable 61, opposite ends of which are connected to the two control systems on opposite sides of the airplane. lVhen the pilot desires to raise say the right side of the airplane he increases the sustaining effect of the control aerofoils 40 and 52 on the right side of the airplane by pulling upon the cable 61 leading to these control surfaces. This causes an increase in the effective length in the tie 55 which operates both planes to a new position of balance in which they are both at slightly greater angles of incidence than they were in their normal attitudes. The direction of the resultant lift is not materially changed and is still approximately along the line 50., but the magnitude of the force now created by the two aerofoils 40 and 52 is materially increased due to the increased angles of the control surfaces. This causes the right side of the airplane to be raised and the airplane restored to its proper attitude. At the time the cable 61 leading to the right side of the craft is pulled by a movement of the control lever towards one side of the airplane, the control cable 61 leading to the control surfaces on the other side of the airplane is released and the spring 63 is permitted to decrease the effective length of the tie between the control surfaces on the left side of the craft to decrease the effective lift created thereby.

For controlling the longitudinal stability or the attitude of the airplane the control lever may be manually operated forwardly and rearwardly to cause the simultaneous and similar operation of the control surfaces on the opposite sides of the airplane. By pull ing the control lever 37 rearwardly in the direction of the arrow shown in Fig. 7 both controlling cables 61 are released thus permitting the control aerofoils to assume lesser angles of incidence and thus resulting in a decreased lifting effect on both sides of the airplane. Since this lifting eifect is directed along the line 50 and is now decreased in value a stalling moment obtains. A directly opposite sequency of operations results when the pilot pushes upon the upper end of the control stick to cause the airplane to dive. As previously mentioned the control stick may also be rotated about its own axis for operating the vertical rudders without effecting the operation of the control cables 61.

In accordance with the embodiment of the invention which has just been described two control surfaces are interconnected to automatically govern one another so that they will assume some normal position of stable balance, each control surface modifying the operation of the other, and one of the control surfaces, as shown, being inclined so that it is given a dihedral inclination. A modified form of construction is shown in Figs. 8 and 9 in which a control aerofoil extends laterally substantially horizontally from each end of the sustaining surface 13. Each control surface 70 is pivoted along a horizontal axis 71 preferably slightly to the rear of the center of pressure which is indicated at 72. The control aerofoil 70 is inclined downwardly at its forward portion and is in the up stream of air flowing out from under the depending fin 73 attached in place on the tip of the sustaining plane 13. As the air M flows upwardly and rearwardly in the direction of the arrow 74 in Figs. 8 and 9, the aerofoil 70 will be at a positive angle of incidence to the rush of air past it and will consequently be normally exerting some lifting effort, the reaction line of which will correspond to the line 50 of Fig. 3 when the control aerofoil is in its normal position. Attached to the rear portion of the control aerfoil 70 are a pair of frame members 75 and 76 in which the controlling vane or aerofoil 77 is pivotally mounted along an axis comparatively close to the leading edge of the vane and in front of its centerof pressure. The control vane 7 7 is inclined to the horizontal so that it eX tends outwardly and downwardly, or in other words, isarranged at a negative dihedral angle. The control aerofoil 77 is provided with anupwardly extending horn 78 to which is attached a spring 79 which normally tends to move the rear part of the aerofoil upward- 1y. An opposite downwardly extending horn 80 is operated by means of a cable 81 which extends through the pivot axis 71 of the aerofoil and over suitable guide rollers to the lower part of the control stick 37 so that the control cable 81 may be manually operated in conjunction with the spring 79 to manually adjust the relative positions of the two aerofoils.

The controlling aerofoils of Figs. 8 and 9 operate to automatically maintain the stability of the airplane in the same manner as the aerofoils shown in Figs. 3 and 4. The controlling surface 77 normally assumes a position at a positive angle of incidence and maintains the control aerofoil 70 at some suitable positive angle of incidence in a position of stable balance in which the line of lift extends to the rear of the center of gravity and corresponds to the line 50 of Fig. 3. In case of a dive the relative positions of the control aerofoil 7 0 in relation to the sustaining surface 13 is automatically adjusted without interference from the control cable 81 since the latter extends through the pivot 71 about which the control aerofoil is moved. The control surfaces 70 and 7 7 maintain their normal positive angles of incidence but since the top of the wing cellule is considerably ahead of the center of gravity in diving, the turning moment about the center of gravity created by the aerofoils is considerably decreased and the tendency is thus for the airplane to automatically right itself. In case of a side slip towards the right in Fig. 9 the lateral component of the rush of air past the inclined controlling aerofoil 77 is comparatively great due to the negative dihedral angle of this aerofoil. There is a considerable depressing effect therefore on the rear of the control aerofoil 70 which automatically causes the two aerofoils 7 7 and 70 to assume some new position in which the lift of the main aerofoil 70 is very materially increased. The efiect of this increased lift is to right the airplane by raising the low side and it will be understood that the controlling surfaces on the opposite side of the airplane will operate in a correspondingly opposite manner.

The angle of incidence of the control surface 7 0 may be manually governed by a manual manipulation, of the control cable 81 which when pulled causes an increase of the angle of incidence of the controlling vane 77 which, due to the air reaction, is elevated so as to cause a decrease in the angle of incidence of the control surface 70. The total lift or air reaction of the two surfaces 70 and 77 will thus be decreased resulting in a corresponding lowering of the side of the airplane on which they are located.

WVhile the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus and that changes may be made in either without departing from the scope of the invention which is defined in the appended claims.

What is claimed is 1. In an aircraft, a controlling surface tiltable to various angles of incidence about an axisinclined to the vertical means for controlling said surface manually and an air vane adapted to rotateon an axis inclined as viewed from the front with respect to the axis of said surface for automatically controlling the position of said surface.

2. In an aircraft, a control surface tiltable to various angles of incidence about a laterally extending axis arranged at a substantial angle to the horizontal, and an air-actuated jfrane for automatically controlling said surace.

3. In an airplane, means for automatically stabilizing the same laterally comprising a control surface and a vane for automatically operating said control surface, said surface and said vane being rotatable about axes angularly related to the vertical and relatively inclined as viewed from the front.

4. In an airplane, a controlling surface pivoted 011 one side of the center of pressure, a second control surface pivoted on the other side of the center of pressure, means interconnecting said surfaces for similar movements so they may be balanced in a normal position, and means for manually varying said interconnection during flight.

5. In an airplane, a fixed wing cellule of considerable height and width, means located adjacent the upper outer portions of said cellule for effecting longitudinal and lateral control of the airplane, said means creating a force in normal flight which is directed angularly downwardly well to the rear. of center of gravity of the airplane.

6. In an airplane, an upwardly extending wing cellule of considerable height and width as compared to its depth and having a height commensurate with its width dimension, comprising a series of fixed lifting surfaces spaced apart vertically a distance equal to several chord lengths, said surfaces exceeding two in number and the intermediate surface or surfaces being of considerably less chord length than the surfaces at the upper and lower portion of the cellule.

7. In an airplane, a wing cellule comprising four planes vertically spaced apart with adjacent planes spaced apart a distance equal to several chord lengths, the upper and lower planes of the cellule being of considerably greater chord length than the intermediate planes, and means for effecting lateral and longitudinal control supported directly upon said cellule.

8. In an airplane, a wing cellule of considerable height'and width and composed of a series of long fixed planes of very small chord width extending out at right angles to the length of flight, means supported on oppositesides of said cellule for effecting directional control and means supported by an upper portion of said cellule operable for controlling the lateral and longitudinal movements of the cellule.

9. In an airplane, fixed main sustaining surfaces, a frame, propelling means supported by said frame, and means for automaticaliy controlling lateral and longitudinal movements of said airplane comprising a control aerofoil, a controlling vane vertically displaced therefrom, the position of which is controlled by the air rush past the same and means interconnecting said control aerofoil and said controlling vane so that they assume some normal angle of incidence in a balanced position. 7

10. In an airplane, a sustaining surface, a frame, propelling means supported by said frame, and means for automatically controlling said airplane laterally comp-rising a control aerofoil, a controlling vane vertically displaced therefrom, the position of which is controlled by the air rush past the same and means interconnecting said control aerofoil and said controlling vane so that they assume some normal. angle of incidence in a balanced position, and means for manually adjusting the relationship of said aerofoils so that they balance each other in some new position relatively to one another. I

11. In an aircraft, a sustaining surface, and stabilizing means therefor comprising acontrol aerofoil, a second control aerofoil connected thereto so that the movement of one is effective on the other, said aerofoils being pivotally mounted about axes which are relatively inclined as viewed from the front andbalanced'in a normal position but being capable of automatic adjustment, and means for manually controlling said aerofoils without interferin with their automatic adjustment.

12. In an airplane, a series of sustaining surfaces, propelling means, and control means only at the outer upper portions of the sustaining surfaces for normally automatically and manually controlling all longitudinal and lateral movements of the airplane.

13. In an aircraft, a system of control aerofoils and comprising an aerofoil pivoted in front of its center of pressure connected with a second control aerofoil pivoted at the rear of its center of pressure, both of said aerofoils being normally at positive angles of incidence and in stable equilibrium.

14. In an aircraft, a system of control aerofoils and comprising an aerofoil pivoted in front of its center of pressure connected with a second control aerofoil pivoted at the rear of its center of pressure, both of said aerofoils being normally at positive angles of incidence and in stable equilibrium, and means for manually adjusting the normal relative relation of said aerofoils to cause a change in their combined lift.

15. In an aircraft, a system of control aerofoils comprising an aerofoil. pivoted in front of its center of pressure, a second control aerofoil pivoted at the rear of its center of pressure, said aerofoils being tiltable to various angles of incidence about axes which are relatively inclined as viewed from the front, and a connection between said aerofoils, both of said aerofoils being normally at positive angles of inciden cc and in stable equilibrium.

In testimony whereof I hereto affix my signature.

WILLIANI F. GERHARDT. 

